1. Field of the Invention
The present invention relates to a video display device and a multi-screen display device formed through the combination of a plurality of video display devices, and more particularly, to a reduction in power consumption.
2. Description of the Background Art
A multi-screen display device obtained by arranging screens of a plurality of projection type video display devices is known as a display device that displays a large video image. While discharge lamps have been widely used as light sources in a projection type video display device, the progress of technology allows the output brightness of a light emitting diode (LED) to fit for use as a light source of a projection type video display device, and thus, LEDs are used these days (for example, see Japanese Patent Application Laid-Open No. 2005-274884).
The output brightness of an LED light source fits for use as a light source of a projection type video display device but, on the other hand, power consumption thereof becomes equal to or more than that of a discharge lamp. Similarly, an increase in power consumption is a problem also in a multi-screen display device formed through the combination of a plurality of projection type video display devices including LED light sources.
The multi-screen display devices are mainly used in monitoring rooms for roads, traffic, plants, and the like in many cases. In those cases, a portion that is not always required for display may exist in the multi-screen display device depending on the time period and display contents. Therefore, the method of turning off a part of power sources for projection type video display devices constituting a multi-screen display device is proposed as the method of reducing power consumption. In this method, however, a video image may not appear instantaneously as required, and the work of an operator may be hindered.